System of control



, R. E. HELLMUND. l SYSTEM OF CONTROL.

APPLICATION FILED MAY 7, 1917 1 $44,762. Patented June 29, 1920.

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WITNESSES INVENTOR WM AfiORNEY I v UNITED STATES PATENT omen.

RUDOLI E. HELIIMUND, OI SWISSVALE, PENNSYLVANIA; ASSIGNOR TO WESTING-HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION 01 PENN-SYLVANIA.

Original application filed September 10, 1914. Beriai No. 880,995.Divided and this application filed May.

Specification of Letters Patent.

SYSTEM OF CONTROL.

7, 1917. serial No. 186,883.

To all whom it may concern:

Be it known that I, Runonr E. Hum.- m UNI), a subject of the (rel-manEmpire, and a resident of Swissvale in the county of Allegheny and Stateof lennsylvania, ave invented a new and useful Improvement in Systems ofControl, of which the following is a specification the presentapplication being a division 0 my copending application, Serial No.860,995, filed September 10, 1914.

My invention relates to systems of control, and it has special referenceto regenerative systems that are adapted to be employed in connectionwith electric railway vehicles and the like.

The object of my invention is to provide a system of the above-indicatedcharacter which shall be simple and inexpensive in construction, andefficient and reliable in operation, and which shall obviate certainoperating difficulties which have heretofore been experienced in suchsystems. More specificallystated, the object of my invention is toprovide simple and reliable means for dynamically braking, with di-'react-current, one or more motors that are embodied in an electricrailway vehicle and that are adapted to be accelerated from analternating-current supply circuit.

in the prior art, various systems have been 1proposed for electricallybraking vehicles t at embody alternating-current motors by arranging thecircuits to adapt the motors to return alternating current to the supplycircuit, or by exciting the motors from the supply circuit andconnecting the armatures through suitable translating devices. However,many operating difficulties and undesirable conditions have arisen,partially by reason of the heavy wattless current and relatively lowpower-factors that obtained. Moreover, in case the supply-circuitvoltage failed, no means for electrically braking the vehicle wasavailable, with the result that the air or other mechanical brakes havebeen inadequate to meet certain emergencies, such as safely bringing thevehicle to the bottom of a long grade.

In the accompanying drawing, Figure 1 is a diagrammatic view of analternating-cub rent system for accelerating a suitable motor; and Fig.2 is a diagrammatic view of the circuit connections employed duringdiwinding T of any suitable type is connected,

and a propelling motor, preferably of the commutator type, which isprovided with an armature A, a main or exciting field winolin F and anauxiliary or compensating fie d winding C. Inasmuch as the particularsystem for accelerating the motor is not material to my presentinvention, none will be described here, and it will be understood thatany suitable and well known system may be employed.

,eference may now be had to Fig. 2, wherein is illustrated the mainmotor, such as is employed in the system of Fig. 1, a braking resistorR, a battery B, a multi-position single pole battery switch 8, adoublepole battery switch 9, a reversing switch RS, of any familiartype, for reversing the battery connections, a bridging resistor 10, anda suitable shunting resistor AR which is disposed in parallel-circuitrelation to the compensating field Winding C. The function of theshunting resistor AR is to reduce the compensating efiect of the fieldwinding C when direct current is traversing the motor, inasmuch as,while the field winding'O affords proper compensation duringalternating-current operation, the motor will, in many cases, beover-compensated during direct-current operation unless the compensatingfield winding current is reduced, as shown in the figure, or in someother suitable manner.

The purpose of the system here shown is to obviate the use of amotor-generator set or other source of ener y for permanently excitingthe field winding F of the main motor during the braking period. When itis desired to dynamically brake the vehicle, the circuits are initiallyarranged as shown in the drawing, with the switch 9 occupying its closedposition, thereby connecting the battery B in circuit with the mainmotor to I operative position, wherein the resistor 10 is disposed totemporarily bridge the battery B, and the switch 9 is opened whereby thebattery 13 is excluded from circuit, wherementum-driven motor willthereafter excite itself in a satisfactory manner, as will beunderstood. If it is desired to charge the battery B duringdirect-current dynamic braking of the vehicle, this may be readilyaccomplished in any suitable manner, such as, by reversing theconnections of the battery B relative to the brakin circuit, by means ofthe reversing switch I13, and preferably shunting a suitable resistor,such as the resistor 10, across its terminals. I

I do not wish to be restricted to the specifie circuit connections andlocation of parts herein set forth, as various modifications thereof maybe made within the spirit and scope of my invention. I desire therefore,that only such limitations shall be imposed as are indicated in theappended claims.

I claim as my invention:

1. In a system of control, the combination with a dynamo-electricmachine having an armature and a field winding, of electric energy meansconnected in series relation with the armature and the field winding forinitiating electrical braking action of said machine, and means forsubsequently excluding said energy means from circuit to permitelectrical braking action of the machine acting as a self-excitedgenerator.

2. In a system of control, the combination with a dynamo-electricmachine having an armature and a field winding, of a'source of voltageinserted in series relation with said machine and having anelectromotive force in the same direction as the machine generatedvoltage to initiate the building-up of such generated voltage.

In testimony whereof I have hereunto subscribed my name this 5th day ofMay,

v RUDOLF E. HELLMUND.

